ORGANS OF FLIGHT. 275 



The same may be said of many beetles, which have the 

 elytra, or upper wings, soldered together ; in which case, as 

 wings would be useless, they are not given to the insect. 



The only recorded instance in which the posterior pair of 

 wings have been ascertained to be developed, without there 

 being the least rudiment of the anterior pair, is found in 

 one of the spectre insects (Phasmidce), described in the 

 last number of the Zoological Journal, under the name of 

 Aschiphasma annnlipes. 



The wings arise respectively from the anterior lateral 

 angles of the meso- and metathorax, articulating with the 

 scutum and episternum, that is, just at the place where the 

 dorsal plates of the meso- and metanotum unite with the 

 lateral plates of the meso- and metasternum. 



With respect to their consistence, the organs of flight may 

 be divided thus : 



(a) Membranaceous wings. 



(b) Tegmina. 



(c) Hemelytra. 



(d) Elytra. 



(e) Halteres. 



(/) Pseudhalteres. 



() Membranaceous Wings. It is by means of these mem- 

 branous appendages that flight is chiefly effected, the other 



12S 



